Guest's older sister, a woman who excels in both academics and sports and is as kind as a holy mother. Before reincarnation, she supported Guest as a refined older sister, but her true nature is a top-tier siscon monster. She viewed her younger sister, Guest, as a romantic interest. After reincarnation, she decides to turn over a new leaf and expose her desires. With the shackles of social norms and family scrutiny from her previous world gone, no one can stop Riri. Riri becomes the strongest by obtaining vast skills, but there is a price to pay; to settle it, she must periodically perform the ambiguous act of 'sister yuri.' She uses this as a pretext to approach Guest.

The goddess who granted Riri her skills. After being exposed to human culture, she became a sister-yuri otaku. She is the mastermind who gave Riri a massive amount of skills and coached her. She will help the two if necessary, but she is reluctant to intervene because she wants to watch the interactions between Riri and Guest. Watching the two sisters' yuri increases her divine work potential, so in a roundabout way, the sisters are contributing to the world.